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cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()

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Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights the
refcount semantics in these operations.

The new API guarantees protection against the cpu-hotplug operation, but
it doesn't guarantee serialized access to any of the local data
structures. Hence the changes needs to be reviewed.

In case of pseries_add_processor/pseries_remove_processor, use
cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the
cpu_present_map there.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Gautham R Shenoy
2008-01-25 21:08:02 +01:00
committed by Ingo Molnar
parent d221938c04
commit 86ef5c9a8e
15 changed files with 62 additions and 61 deletions
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10
kernel/cpu.c
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@ -48,7 +48,7 @@ void __init cpu_hotplug_init(void)
#ifdef CONFIG_HOTPLUG_CPU
void lock_cpu_hotplug(void)
void get_online_cpus(void)
{
might_sleep();
if (cpu_hotplug.active_writer == current)
@ -58,9 +58,9 @@ void lock_cpu_hotplug(void)
mutex_unlock(&cpu_hotplug.lock);
}
EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
EXPORT_SYMBOL_GPL(get_online_cpus);
void unlock_cpu_hotplug(void)
void put_online_cpus(void)
{
if (cpu_hotplug.active_writer == current)
return;
@ -73,7 +73,7 @@ void unlock_cpu_hotplug(void)
mutex_unlock(&cpu_hotplug.lock);
}
EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
EXPORT_SYMBOL_GPL(put_online_cpus);
#endif /* CONFIG_HOTPLUG_CPU */
@ -110,7 +110,7 @@ void cpu_maps_update_done(void)
* non zero and goes to sleep again.
*
* However, this is very difficult to achieve in practice since
* lock_cpu_hotplug() not an api which is called all that often.
* get_online_cpus() not an api which is called all that often.
*
*/
static void cpu_hotplug_begin(void)